Work

Summary

The component of the force parallel to the displacement is what matters.

is the scalar product of force and displacement.

W = F̅Δs cos θ

is the force-displacement path integral.

W =

⌠⌡

F · ds

Work-Energy Theorem

Work is done when the energy of an object changes form (energy transduction).

Work is done when energy is transfered from one object to another (energy transfer).

Work is a change in energy.

abbreviated version

W = ΔE

algebra version

F̅Δs cos θ = ΔE

calculus version

⌠⌡

F · ds = ΔE

Units

The SI unit of work and energy is the joule, named after the English physicist and brewer James Joule (1818–1889).

[J = Nm = kg m2/s2]

The electron volt is an acceptable non SI unit of energy. It is used for some applications in electromagnetism; solid state, atomic, nuclear, and particle physics; and related sciences like biophysics, chemistry, and astronomy. An electron volt is the work done a particle with one elementary charge when it is moved between two points with a potential difference of one volt. It is described in more detail in the section on electric potential (a.k.a. voltage).